Generally, a GaN-based nitride semiconductor is applied to electronic devices that are high-speed switching and high power devices such as optic elements of blue/green LEDs, MESFET, HEMT, etc. In particular, the blue/green LED is under a state in which mass-production has been already progressed and a global sale is being exponentially increased.
Such a GaN-based nitride semiconductor is grown up usually on a sapphire or SiC substrate. At a low growth temperature, a polycrystalline layer of AlxGa1−xN is grown as a buffer layer on a sapphire substrate or a SiC substrate. After that, at a high temperature, a good quality GaN-based single crystalline layer is grown on the buffer layer, thereby fabricating the GaN-based nitride semiconductor.
Meanwhile, to improve the performance of the GaN-based nitride semiconductor and assure the reliability thereof, an innovative buffer layer is researched and the GaN-based nitride semiconductor fabrication method has been studied very actively.